JOURNAL OF NUCLEAR SCIENCE AND TECHNOLOGY
Year:2016 | Volume:- | Issue:77 |Papers Count:11

177Lu owing to its favorable nuclidic characteristics, such as tl/2=6/73d and Eβ (max)= 497 keV and ease of its large-scale production using medium flux research reactors, is an attractive radionuclide for various therapeutic applications. In this study 177Lu with the radionuclide purity of >99. 9% was obtained by thermal neutron bombardment (4×1013n/cm2. s) of 176Yb target through the 176Yb(n, γ ) 177Yb      177Lu process. The method of separation of 177Lu from macro amount of Yb target was based on extraction chromatographic (EXC). The extractant used in resin was di(2-ethylhexyl) orthophosphoric acid (HDEHP). Finally, (177Lu) with a specific activity of 230. 1 MBq (6. 22 mCi) was prepared without the addiation of any carrier radionuclide. The process provides a separation yield of 75% 177Lu and a decontamination factor of 2000. The whole process to prepare NCA 177Lu takes almost 1. 5 hours. The resultant NCA 177Lu can be used for preparation of NCA 177Lu labeled radiotherapeuticals.

Acidithiobacillus species is used in bioleaching process of metals such as uranium, copper, nickel. The purpose of this study was to develop an effective protocol using facilities available for preservation of isolated native bacteria involved in uranium bioleaching. In this study, the bacteria involved in uranium bioleaching AEOI Laboratory were cultured, purified and stored at 4 and-80° C. Then, variation of pH, Eh, growth and biochemical characteristics were examined after 6 months of storage and compared with the bacteria before using the preservation methods. The results indicated that the preservation of the bacteria within 6 months at selective temperatures did not have any effect on the biochemical characteristics of the bacteria. In addition, no significant changes were observed in the variation of pH, Eh and growth of bacteria, before and after the preservations. The results suggested that 6 months preservations of native bacteria at 4 and-80° C, had no effect on the ability of bacteria in bioleaching process.

In this study, initialy the effect of time on the removal of strontium from aqueous solutions by continuous electrodeionization (CEDI) with H+ form resin was investigated. Then, by using an orthogonal L9 array in the Taguchi method, the effect of voltage, flow rate and feed concentration on the removal of Sr and Cs from aqueous solutions by the CEDI with the saturated resin was applied. The analysis of variance (ANOVA) method was used to evaluate the relative effect corresponding to each factor. The results showed that by increasing the applied voltage and decreasing the flow rate improve the performance. The effect of input voltage was more significant and the feed concentration did not have any perceptible effect on the Sr and Cs removal efficiency. The removal of both elements from binary solutions were also investigated. In this experiment, the removal efficiency of Sr was also found to be higher than those of Cs. Based on the results, electrodeionization was considered to be effective for Sr and Cs removal from aqueous solutions.

Multiphase flow metering, has been one of the most important issues in oil/gas industry, since the early 80s. Oil-water two-phase flow, shows off specially in flow meters that work based on separation of oil-water-gas three-phase flow into liquid (oil-water), and gas streams just before measurement. Here, at first, two-phase flow homogenizer loop (TPFHL) as a solid-liquid as well as liquid-liquid homogenizer loop, is introduced, and then its performance accuracy is verified by counting the transmitted gamma-rays of a 137Cs radioactive source. The acceptable results, compared to the reference data, endorse the capability of the introduced loop in conjunction with the gamma densitometer for volume fraction measurement in a wide range of two-phase mixtures. Moreover, the instrumentation usage for oil-water component fraction measurement was simulated, using an 241Am gamma source which showed a good agreement with the authentically published results.

In this paper, after reviewing the history of plasma focus devices, the plasma focusing issue is raised and then the results of comparisons between two new Mather type plasma focus devices are presented. The main aim of this investigation was to study the effect of the energy bank capacitance o C, and the circuit inductance o L, on the energy of the hard X-ray of Mather type devices. This invetigation showed that the effect of the o o L C reduction, on the increment of the hard X-ray energy, is much more than the effect of the discharge energy variation. That is, in spite of 55% discharge energy decrement, a 40% reduction of the o o L C, leads to 227% increment of the hard X-ray energy. That is observed in a Mather type device designing. It should be mentioned that the more energy consumption is not a neccesary condition for a more energetic hard X-ray emission.

In radiotherapy, the delivered dose to a target tissue should be of high accuracy, where any inaccuracy in the delivered dose can affect the treatment outcomes. Radiochromic films, in this respect, have an essential role in the verification and quality assurance of the radiotheraphy treatment. Gafchromic EBT2 films are widely used in radiation dosimetry due to their advantages such as high sensitivity, good reproducibility, high spatial resolution, easy readout and portability. The first step in applying these films in dosimetry is preparing the calibration profile and determining the uncertainty and absolute error of the films calibration protocol. In this paper, first, the uniformity of a suitable flatbed scanner which is used in dosimetry readout procedure is studied. Then the calibration process of the EBT2 film is carried out using Cobalt radiotherapy. After the detailed specification of error and uncertainty of measurements, the used protocol is evaluated. Also, the analysis of the films is performed by homemade functions using the Matlab software and program along with the image processing toolbox. The percentage depth dose curve of high energy electron beam obtained by the EBT2 film is compared with the standard ionization chamber data. The results show that within the central scan region (20×20 cm2) the scanner nonuniformity is less than ± 1%, and no correction method was required. By the use of the described protocol, the error for the dose measurements was evaluted to be less than 1% for a uniform field. A comparison of the percentage depth dose curves obtained from the ionization chamber and EBT2 film shows a 4% difference in values between two curves. The protocol described in this paper is recommended for accurate dosimetry using EBT2 film.

The aim of this research was the synthesis of 111In-THPP, and its evaluation as a new imaging agent. The 111In-THPP radiotracer was synthesized by 111InCl3 and 5, 10, 15, 20-tetrakis (4-hydroxyphenyl) porphyrin) (THPP) in solution for 60 min at 80˚ C. In-111 radionuclide was produced from proton bombardment of natCd target using 30MeV protons and 150μ A current. Separation was achieved using ion chromatography method with the separation yield of >98%. In order to determine the radiolabeling yield (or metallation) radio thin layer chromatography (RTLC) and high performance liquid chromatography (HPLC) were used (with the radiochemical yield of >99% for both methods). The radiolabeled compound was injected to the healthy rats and the biodistribution studies were performed using scarification. The single photon emission computed tomography (SPECT) imaging within 2-24h shows the accumulation of 111In-THPP in the kidneys, compared to other organs. 111In-THPP is essentially excreted via kidneys. Due to relatively low liver uptake and kidney wash-out, 111In-THPP could be a potential agent for imaging.

The morphology of zirconium sponge formed during the Kroll process could be more important due to its effect on composition, amount of impurities and efficiency of the sponge durability in the subsequent intermediate processes. In this research, various samples were prepared from different stages of the process and different zones of the products. In order to evaluate the products, scanning electron microscopy (SEM) and X-Ray diffraction (XRD) techniques were used. XRD analysis of the zirconium sponge showed that the amounts of magnesium chloride and retained magnesium in sponge texture were at a high level after the reduction process and were distributed non-uniformly in various parts of the sponge in which the amounts of impurities in the center was higher than the other parts. Also, examination by the scanning electron microscopy showed that the prime morphology of the zirconium sponge particles is irregular. Chemical analysis indicated that the excretion of magnesium impurities from the sponge will be more desirable in the distillation process, when the sponge morphology is in needle– like shape. If there is not enough time for the distillation process, the amount of magnesium and chloride impurities in the center of zirconium sponge will be higher in comparison to the other areas. So, for maximum elimination of such impurities in the distillation process, sufficient time duration has to be considered. Despite the fact that the distillation process is time-consuming and expensive, the impurity elimination compared to the proceses of chemical purifying is more favourable.

Crystal of LiF were grown by a home-made Czochralski system using MgF2 (0. 05%), LiOH (0. 1%) and Li2CO3 (0. 05%) powders as the impurities after purification by the zone-melting method. Another crystal was also grown with raw materials with the normal purity of 99. 995%. The grown crystals were found to be colorless and transparent with no cracks. In order to obtain a high concentration of F2+ centers and small concentration of colloids and parasitic aggregate centers, the grown crystals were subjected to the multi-step ionizing irradiation treatments. At the same time, maintaining the highest possible density of F2+-like centers and small cluster centers caused the effective thermal stability of F2+-centers and in particular reduced the formation of the electron color centers which improved the stability of the optical features of the modified LiF: F2+** crystals. As a result, acting as a color center laser medium. A comparing of the features of crystals shows that their optical characteristics are the same as the other samples. The XRD properties of the grown crystals were also investigated for the comparison. They indicated the Faced-Centered Cubic (FCC) structures of the crystals. In addition, the inductively coupled plasma (ICP) analysis was used to measure the Mg2+ ion concentration. The emergence of OH-peaks was specified by a FTIR spectrophotometer. In a long run, the spectroscopic characteristics of the new F2+-centers in LiF: OH, Mg crystals were also studied.

Iran is the fourth largest cement producing country in the world, and one of the pioneers in this industry. For this reason, study and further research in the fields related to the cement industry are of great importance. The cement conveyor on-line analyzer systems use the prompt gamma neutron activation analysis (PGNAA) method. In this paper, based on the same method a comparative analysis for three samples of cement with certain elements was carried out. Prior to the experiment, porameters such as moderator thickness and size of samples were optimized by the MCNP code. In this experiment, the relative counts of the obtained spectra were calculated and plotted by subtraction of the continued background of three cement samples for each of the main peaks of the energy (3. 539 and 4. 935MeV for Si, 4. 418 and 6. 419 MeV for Ca, 5. 92 and 7. 630 MeV for Fe and 7. 725 MeV for Al). Then, the qualitative and relative analyses of the main elements of cement were performed and compared with the actual values. At last, according to the calculated errors for each element of the peak energy, feasibility studies and laboratory experiments were carried out. These experiments were carried out by an Am-Be neutron source with an activity of 555GBq (15Ci) and a NaI detector.